摘要
针对深部低渗透储集层水力压裂裂缝扩展问题,利用现场采集的深部低渗透岩芯样本开展了水力压裂模型试验,利用CT扫描技术和自行开发的三维重构算法,提取并分析了三轴应力和水压力作用下,低渗透岩石水力压裂裂纹的扩展与空间展布规律,探讨了不同岩性、地层应力对裂纹扩展与空间形态的影响。研究表明:岩性、水平应力比对裂纹起裂压力以及裂纹形态有显著的影响。起裂压力均比围压应力大;在最小水平应力相近的情况下,初始应力比越大,裂纹扩展越明显,起裂压力越小;岩石破裂时出现了一条与最大水平应力平行的主裂纹,伴随着明显的中断、扭曲和分叉现象。
In order to expose the cracks propagation law induced by hydraulic fracturing in deep low-permeability reservoir stratum, a series of hydraulic fracturing physical tests of low-permeability core samples collected in situ are carried out. Using CT scanning technology and self-developed three-dimensional reconstruction algorithm, the cracks propagation and special distribution laws are featured in low-permeability rock subjected to triaxial stress and hydraulic pressure. The effects of lithology and crustal stress on cracks growth distribution features are exposed. The results show that the lithology of rock and ratios of horizontal crustal stress have great influences on initiation stress and geometric distribution features of cracks growth. The initiation pressure is always greater than the confining pressure. When the minimum horizontal crustal stress is similar, the bigger ratio of horizontal crustal stress induces more fractured cracks and small initiation stress. The direction of failure main cracks is consistent with the direction of maximum horizontal crustal stress. The main cracks appear in the middle of samples accompanied by noticeable interruption, distortion and bifurcation.
出处
《采矿与安全工程学报》
EI
北大核心
2013年第5期739-743,共5页
Journal of Mining & Safety Engineering
基金
国家重大专项重点项目(2011ZX05011)
胜利油田分公司科技攻关项目(YKC1207)
山东胜利油田低渗透油藏综合利用示范基地建设项目(YKC0720)
国家重点基础研究发展计划(973)项目(2010CB226804
2011CB201201)
国家国际科技合作专项项目(2012DFA60760)
关键词
水力压裂
低渗透
CT扫描
裂纹扩展
hydraulic fracturing
low permeability
CT scanning
crack propagation
